Drivers of automotive vehicles, including, e.g., passenger cars, vans, buses and trucks, depend on rear view mirrors for visual information of the road and surrounding area. This information is vital to the safety of the driver and any passengers transported in the vehicle. Often bright light from, for example, another vehicle's headlights or sunlight is reflected into the rear view mirror causing glare and a reduction in the visual acuity of the driver. Therefore, the potential safety of the driver and passengers will be at risk.
In the past, to alleviate the glare problem, electrochromic mirrors having variable reflectivity have been commercialized as rear view mirrors for automotive vehicles. Electrochromism is a reversible color change phenomenon of a material induced by an applied electric current. In an all solid device, the device consists of several layers of thin film coatings. A typical device consists of a glass substrate on which a transparent conductive indium tin oxide (ITO) coating is laid down. An anodic electrochromic layer is coated on top of the ITO conductive layer, followed by a solid state electrolyte, then a cathode electrochromic layer. An aluminum reflector is used as the other conductor for completing the current circuitry. An electronic control switch is used for controlling the transmission of the electrochromic layers, and thus, the reflectivity from the aluminum reflector to achieve the variable reflectivity feature of this prior art device.